Wandering, sway bars, alignment, ride height, oh my!!

[mhughes]

Sounds like you planned it out very well.

[Kurt Averill]

I hope so, we'll know for sure in a couple of weeks. I always thought something wasn't quite right - always thought the coach should be a little less work; especially in the wind passing trucks, and this thread made me understand why. It is really amazing to read through the whole thing and see how it all came together, I am thankful to you, Van, Crah, and all of the others who worked it all out so that the rest of us can benefit from your efforts.

[sjholt]

Getting back on the total caster with 2 degree shims.
My caster is at 6.3 degrees now.
I think I read somewhere that Monaco set the caster on these mid 90's at 4.5 degrees so it must be true at least on my 96 Windsor.

Skip H.

[10Boomer]

Originally Posted by sjholt

Getting back on the total caster with 2 degree shims.

My caster is at 6.3 degrees now.

I think I read somewhere that Monaco set the caster on these mid 90's at 4.5 degrees so it must be true at least on my 96 Windsor.



Skip H.

The castor varied from coach to coach.

[zmotorsports]

Originally Posted by Kurt Averill

Here is a photo of the front - with the suspension hanging. The one in the back is similar - a little easier to build the bolt on bracket in the rear as the h-frame is wider in the back and of course I had to match the length of the existing panhard bar. I built mine with some 3/4 X 3/4 Aurora CM heim joints - 1-1/8 X .095 CM tubing, Meziere CM tube adaptors. The brackets are made with 2" square tube, the appropriate tabs for the heim jts and 3/8" plate. I had to weld the chassis end on. I have about 30 or so miles on my first test run and everything seems to be working fine so far, definitely a vast improvement.

Nice job. I will be curious to hear of your experience after your long trip. Please give us an update afterwards.

Mike

[Vanwill]

Originally Posted by Kurt Averill

I hope so, we'll know for sure in a couple of weeks. I always thought something wasn't quite right - always thought the coach should be a little less work; especially in the wind passing trucks, and this thread made me understand why. It is really amazing to read through the whole thing and see how it all came together, I am thankful to you, Van, Crah, and all of the others who worked it all out so that the rest of us can benefit from your efforts.

Kurt, I have tremendous respect for what you have done. Adding a second Panhard rod is the solution that should have been done when the chassis was first designed. It is also the method that I wanted to do on my own coach, but simply could not figure out a way to make it work that did not involve some really difficult out-of-position, but very critical, welding. Your solution is very impressive, and I expect you will get the same great results as others have gotten from the Watts link setup. All that is required is that you devise a method, any method, to prevent the H-frame from squirming around under the coach and "steering" it.

Kudos for your technical skill!!

[Kurt Averill]

Originally Posted by Vanwill

Kurt, I have tremendous respect for what you have done. Adding a second Panhard rod is the solution that should have been done when the chassis was first designed. It is also the method that I wanted to do on my own coach, but simply could not figure out a way to make it work that did not involve some really difficult out-of-position, but very critical, welding. Your solution is very impressive, and I expect you will get the same great results as others have gotten from the Watts link setup. All that is required is that you devise a method, any method, to prevent the H-frame from squirming around under the coach and "steering" it.

Kudos for your technical skill!!

Thanks Van! I appreciate it. I tried to simplify the position welding as much as possible to take some of the pain out of it, was a bear, but most of the burns are almost healed up...

[Vanwill]

Most of you will probably remember Z-Mike's thread about mods to his 2003 Dynasty began early with correcting the "thrust angle". That is essentially an alignment task, which seeks to have the wheelbase exactly the same on both sides. In his case, his rear axle was not perfectly square to the length of the coach, and he corrected it by shortening the trailing arms on one side. He did an excellent job of that, in spite of all the flaming he got from some PAP's (Pontificating Apocalypse Predictors).

One thing that made that job somewhat easier for him was that he knew someone with a portable laser device that he could use to measure the wheelbase very accurately on both sides. He could therefore adjust the length of the trailing arms on one side that very small amount required (approx. 1/8") and be assured his outcome would correct the problem.

I have decided that my coach has a problem similar to his. My coach has always pulled noticeably to the right. As you know, I'm not a great fan of spending $350 on an alignment that 90% of the time is just an adjustment of toe-in. So, I have just lived with the pulling to the right for four years now, knowing I would never wear out a set of tires--they would always age out long before wearing out. That has proved to be the case.

However, now I see that my Driver Side rear tires are SIGNIFICANTLY more worn than those on the Passenger side. Before I replace them, I want to correct whatever is causing the abnormal wear, and I suspect it is the "thrust angle" problem that Z-Mike discovered.

Unfortunately, I cannot find an accurate enough way to measure the amount the trailing arms need to be shortened (or lengthened). The truck alignment shop I deal with says they can give me an ANGULAR measurement of how much it is off, but not a wheelbase measurement. That would be sufficient, and I could calculate the linear amount. Unfortunately, the shop says it would cost almost as much as a four-wheel alignment to furnish me that figure. Then I would have to have them do it again when I was finished to check the result.

So, I am going to fabricate two adjustable-length trailing arms to substitute for the two existing ones. They will be similar to the trailing arms used on some large OTR tractors. I will be machining two 1-3/8 x 12, 4140 heat-treated RH/LH screws to fit inside the 2 x 2 x 1/4 trailing arm. There will be a hex section in the middle to allow a large wrench to turn them. The ends of the trailing arms will have welded-in inserts (RH/LH). There will be locknuts for the RH and LH portions of the 1-3/8 screws.

SO, the reason for my post? There are a lot of really talented folks contributing to this forum and this thread. If you have any ideas about how I might better accomplish this task of accurately MEASURING the wheelbase difference on the two sides, or a better way to correct the thrust angle, please chime in. You have all helped me in my quest for better handling coaches, and before I do what I have planned, I want to get your input.

OTOH, for all you PAP's that want to tell me how I'm about to imperil my own life, risk the lives of others, and those of anyone who might travel with me, increase my "carbon footprint", contribute to depleting the ozone layer, and increase world hunger...please get a life and stifle yourself. Only legitimate suggestions, please.

[barmcd]

Van, can't you use a laser measuring tape? With a device like this you should be able to measure between two points with pinpoint accuracy.

[CrazyKnight]

Van and I discussed the measuring issue and the problem with most of the laser measuring devices, such as above, is they are not accurate enough for the job. I have found one reasonably priced that is +\- 1mm. The more expensive ones that are commercial units are just that MUCH MORE expensive. Measuring from the axle housing weld to the center of the bolts on both trailing arms could work but you need an accurate way to measure. I would think if you could get it +/- 1/32" that should be sufficient.

Building the adjustable trailing arms in a fashion used by OTR trucks and installing them at the same length setting then have a reputable shop do a 4 wheel alignment could take any guess work out of the measuring process.

GREAT now I have something else to check on my coach.
I just ordered 20 ATRO bushings and will install them late September. That will be fun.

Keep us posted Van !

[Dennis_K]

I have set the thrust angle many times on 100" wheelbase Jeeps but never tried the motorhome. Could be difficult to get closer than .063" with a tape measure. I always started by getting the rear axle centered in the chassis then square with the chassis using a center point at the front of the frame and measuring back to each side of the rear axle. Need to do get the front axle square too which can be done similar to the rear or by using the wheelbase measurement. Once front and rear are square the wheelbase measurements should be equal. Setting just the wheelbase will not necessarily square the axle to the chassis (thrust angle).

Dennis

[Vanwill]

Originally Posted by Dennis_K

I have set the thrust angle many times on 100" wheelbase Jeeps but never tried the motorhome. Could be difficult to get closer than .063" with a tape measure. I always started by getting the rear axle centered in the chassis then square with the chassis using a center point at the front of the frame and measuring back to each side of the rear axle. Need to do get the front axle square too which can be done similar to the rear or by using the wheelbase measurement. Once front and rear are square the wheelbase measurements should be equal. Setting just the wheelbase will not necessarily square the axle to the chassis (thrust angle).

Dennis

Good points, Dennis, especially about squaring the rear axle to the frame. I think I'm just going to end up making the new trailing arms, and leave it to the alignment shop to do the 4-wheel alignment. I cannot imagine it could be out more than .25", and if I make two new trailing arms with a +/- range of .50", that will surely cover it.

Don't know why I never thought of the 3-point measurement, but I'll try that. Regardless, I think I'm still going to make the new trailing arms and get the 4-wheel alignment. I looked at how they do it with lasers, and I think it should be quite accurate.

[Vanwill]

I do not remember how I THOUGHT I knew this, but for some reason, I have always thought the trailing arms were made from 2 x 2 x 1/4 tubing. I know they are really heavy when you remove them, and I cannot imagine anything that heavy having a 1/8 wall. But I recently had a conversation with a fellow who had some reason to drill a hole in the trailing arms on his 04 Diplomat and he says he is sure they are only 1/8 thick.

If someone does not know the answer, I guess I'll have to go drill one myself. I'm going to look in some of my metals books and see if the corner radius will identify the thickness.

[mhughes]

1/8" x 2" x 2" tubing has very square corners. Easy to identify. No where near strong enough for trailing arm tubes.